A mode dependent chroma intra smoothing algorithm for emerging HEVC standard

In this paper, a mode-dependent chroma intra smoothing algorithm for HEVC is proposed. As in other hybrid video coding frameworks, discontinuity between prediction samples and reference pixels on the edge of the current block may cause by intra prediction. Intra smoothing on the prediction samples is necessary to reduce discontinuity between prediction samples and reference pixels on the edge of the current block. In the current development of HEVC, mode-dependent intra smoothing (MDIS) has been present based on the size of prediction unit (PU) and the intra prediction mode. However, the MDIS is just applied on luma pixels. After our observation, the chroma pixels also need to be smooth. Generally, chroma pixels seem smoother than luma pixels. Therefore, it should apply a different filter to chroma pixels. The experiment result shows that mode-dependent intra chroma smoothing can improve the overall coding efficiency. Comparing the experiment result of the three sets of intra smoothing filter, it is concluded that the [1 4 1] filter can bring better coding efficiency than the [1 2 1] filter and [1 3 1] filter for intra chroma smoothing.